Enterprise SQL Scenarios

Introduction

Capstone scenarios combining everything — design + scale + security + ops. The kind of question a staff engineer answers in 30 minutes on a whiteboard.

Understanding the topic

Core concepts to understand:

• Design a global, multi-region SaaS DB layer.
• Build an event-sourced ledger from scratch.
• Re-architect an exploding monolithic DB.
• Onboard an enterprise customer with strict compliance.
• Cut DB cost 50% without breaking anything.

Syntax reference

Visual workflow / architecture:

Capstone framework
 1. Clarify scale, SLAs, compliance.
 2. Sketch architecture.
 3. Identify risks (consistency, perf, ops).
 4. Pick simplest viable design.
 5. Define rollout + rollback + monitoring.

Real-world use

Staff and principal engineers solve these for a living. Practicing them turns mid into senior, senior into staff.

Best practices

• Always start with constraints (scale, SLA).
• Make assumptions explicit.
• Plan rollout, rollback, observability.

Hands-on exercise

Interview preparation — practice these questions:

• Q1. Multi-region SaaS DB design.
• Q2. Event-sourced ledger blueprint.
• Q3. Re-architect a monolith DB.
• Q4. Compliance onboarding plan.
• Q5. 50% cost cut plan.